As an eBay regular and I know my way around I'd say I do just fine... or after sharing this info Jim will be doing a little eBay business :)
Here are recent sales (sold) 7.3 injectors...
https://photos.app.goo.gl/trWkpLa80DtJSB782
That's what I was going to say... folks are saying good used\cores are like 10 bucks but you say keep instead of getting this cheap cores and sending them back... FYI I looked on eBay and folks are buying and selling them for a lot more the then 10-15 bucks... goes back to things just don't add...
I guess people must have more money to through away then me.... You'd thank folks would take the time to get almost a 50% ”rebate”.... Maybe a trip to UPS is just to intimidating....
...So say $20 a piece or $160 as set no would bother...
I'd say there is more to the story.... My guess is Good cores are not as easy and cheap to come by
No "easy" way. Try and unbolt the top and bottom bolts remove and reinstall (easier said then then done) . I'd go back with Dorman or International improved up-pipes and be done with the issue.